The present invention relates to a feed and feed additive for livestock, poultry and nursery fishes for increasing disease resistance, particularly, pseudorabies resistance, which comprise safe and natural substances having health improvement and weight gain effects.
Pseudorabies is an acute infectious disease caused by a kind of herpesvirus, which is called Aujeszky's disease derived from the name of inventor who identified the virus.
The disease shows a local and sharp itching symptom on infected animals such as cattle, horse, goat, sheep, rabbit, dog, cat, mink, fox, rat and so forth except swine. The disease paralyzes the a medulla, pharynx and chaps, and causes salivation, dyspnea, abnormal heart beating and death. Reared swine are infected easily, but almost all of them recover from the disease. In a highly humid region, many infected swine in 30 to 80 Kg. of weight have complications with pneumonia and die. Generally, the death rate due to the disease is high in piglets.
In the fields of livestock, poultry and fish, the economic loss caused by diseases due to a poor sanitary environment is very high. This is especially so in the field of swine breeding, which increases in scale every year. A death rate of 1% or more or a product loss of dressed carcass results is a serious negative factor.
For example, in a livestock farm having 100 female pigs, each of which breeds 12 piglets twice a year, the yearly production of the farm will be calculated as 2,400 piglets in total. However, if each mother pig loses three piglets at each breeding, 600 piglets will be lost in total. If the unit price of the piglets is 10,000 when they are sold to a slaughter-house, it means a loss of 6,000,000 a year. Accordingly, control of the health of piglets is an important factor in running a livestock farm.
When symptoms of Aujeszky disease appears in piglets, they must be immediately isolated from healthy piglets or disposed of in order to prevent further infection of the healthy piglets. Non-infected piglets kept a closed hogpen must be transferred to a larger space. Infected breeders, hogpens, utensils, feeds and so forth must be disinfected to prevent further infection. The sick piglets must be dosed with a large amount of antibiotics, synthetic antimicrobial substances, vitamins, minerals or eutrophic medicines in order to prevent complications of the respiratory organs such as pneumonia.
Further, attenuated vaccine or inactive vaccine has been dosed experimentally.
Increased medication is not effective and causes a depreciation of commercial value of livestock products and a reduction of safety due to residual medicines.
Vaccination prevents diseases, but does not prevent infection or carrying of a wild strain of a disease.
In livestock farms, It is impossible to resolve all diseases (including pseudorabies) by using vaccination and antibiotic medicines. If it could be done, it would require many kinds of medicines and great expenses.